1. Field of the Invention
The present invention relates to an improved hydraulic jack device which particularly provides improved outer cylinder, base seat, oil passage and soft tube device placed in the outer cylinder for use of the present invention in inclined positions, and in addition, eliminates the general defects of known hydraulic jacks.
2. Description of the Prior Art
The known hydraulic jacks are varied in type but can generally be classified into three main types, namely, the integral type, the sectional type, and the particular purpose type. The structure of the jacks generally comprises three main parts, namely, the jack body, the plunger pump and the oil passage. To make clear the structure and defects of the known hydraulic jacks, the example of a vertically standing hydraulic jack is hereby described and illustrated. The jack body and the plunger pump of the hydraulic jack are longitudinally arranged and the oil passage is bored in the base seat under the jack body and the plunger pump, permitting the oil passage to pass and make communicable the oil between the plunger pump, the outer cylinder and the inner cylinder of the jack body.
Referring to FIG. 1, where in is shown the vertical sectional view of the known hydraulic jack. Its main structure comprises a jack body 1, a base seat 2, a plunger pump 3, and an oil passage 4 which is used for conducting the oil between the jack body and the plunger pump. The jack body further comprises mainly an outer cylinder 5, an inner cylinder 6, a ram 7 with auxilliary screw (not shown), a saddle 9 attached to the top of the ram and a flange 10 which encases the inner cylinder 6 and the outer cylinder 5. The outer cylinder is cylindrical in shape, the upper extremity thereof is welded to the flange 10, and the lower extremity thereof is welded to the base seat 2, and on the cylinder wall thereof is bored an oil filling hole. Conventional method is to fill the oil container with oil then forever seal the oil filling hole, other methods are to use rubber stopper and screw to tightly seal the hole. Further, the inner cylinder has a ram whose function is similar to that of a piston, when high pressure oil flows in through a hole on the wall, the bottom of the ram is pushed and it rises slowly. Generally an auxilliary screw is attached to the ram for adjusting the head of the jack under particular condition; on the ram is disposed a saddle to support the object to be raised. In addition, the inner cylinder 6 of known jack is screwed or welded to the base seat, generally the lower extremity is equipped with copper cushioning material and is directly communicable with a high pressure oil passage. On the wall of the inner cylinder 6 is an oil releasing hole 11 and an air discharging hole 12. The function of the oil discharging hole 11 is to permit the high pressure oil to discharge to the outer cylinder 5 through the hole, when the ram, being pushed by high pressure oil injected into the inner cylinder 6, rises above the oil discharging hole 11, thus maintaining a constant head for the jack and avoiding the ejection of the ram out of the inner cylinder or the collision with the flange. The function of the air releasing hole is to avoid the existence of a vacuum state created in the inner cylinder 5 and the outer cylinder 6 due to the reduction of the oil amount in either the inner cylinder or the outer cylinder, or the up and down movement of the ram (piston), which influences the movement characteristic of the jack.
The construction of the plunger pump adjacent to the jack body further includes a lever support 13 that can be inserted with a swinging lever, a hinge bracket 14 and a plunger pump 8. To have a clearer understanding of the operation of known hydraulic jack, please refer to FIG. 2 which shows the oil passage of the jack. When employing the jack to lift heavy object, insert the handle lever to the lever support 13 and start the plunger pump. When the plunger of the plunger pump rises, the oil from outer cylinder 5 flows into the plunger cylinder through the oil passage and check valve, when pressurized, the oil flows into the inner cylinder 6 through another check valve, driving the ram to move upward, thus, after repeated exercise of the plunger pump, the object can be lifted by the saddle by means of the ram, or be moved along the desired direction. To lower the ram 7, simply open the valve rod of the oil releasing valve on the base seat 2, and the high pressure oil will be released from the inner cylinder to the outer cylinder, and this completes a cycle of operation of the jack.
The members of the known hydraulic jack mentioned above are mostly casted or made of iron and because of the members and the assemblage thereof, the jack has the following defects and/or disadvantages: a complex manufacturing process, because the members are mostly assembled by welding, oil leak easily happens and thus influences the head of the ram of the jack, and the remaining oil amount cannot be known, therefore the characteristic of the jack cannot be qualitatively and accurately guaranteed. Further, because the oil passage is directly bored in the base seat or the like, if the surface area of the base seat has to be enlarged to avoid the toppling of the jack frequently because of deviation of the center of gravity in the process of loading the jack, the oil passage has to be lengthend, therefore, the difficulty of boring passage in the base seat is greatly increased. Besides, the iron dust in the oil passage in the base seat of the prior art hydraulic jack cannot be completely cleared, the working agent oil of the jack will be contaminated easily, causing damages to the members and influencing the characteristic of the jack. In addition, the defects and/or disadvantages of the prior art hydraulic jack, because of the limitation of the above-mentioned structural members, also include easy leakage of oil in the outer cylinder and difficulty in replacing it, incapability of being willfully used in inclined positions, easy toppling when being used, base seat being too thick, etc. A lot of inconveniences occur when being used. Therefore, a kind of new hydraulic jack which does not possess the above-mentioned defects or disadvantages of the known hydraulic jack urgently needs to be developed.